Variably ventilated propeller

ABSTRACT

Disclosed herein is a marine propulsion device comprising a propeller shaft supported by a lower unit and extending rearwardly through an exhaust gas opening in the lower unit, a propeller having a hub adapted for discharging exhaust gas there through and mounted on the rearwardly extending propeller shaft for common rotary movement with the propeller shaft and for axial movement relative to the propeller shaft between a first, forwardly located position and a second position located rearwardly of the forward position with the propeller spaced axially rearwardly of the lower unit exhaust gas opening, together with means biasing the propeller toward the rearward position.

United States Patent Shimanckas 1 Aug. 28, 1973 VARIABLY VENTILATED PROPELLER Prima Examiner-Everette A. Powell Jr. 75 l t Willi .sm k w k 1 men or L J mam an egan Attorney-Robert E. Clemency et al.

[73] Assignee: Outboard Marine Corporation,

Waukegan, 111. [57] ABSTRACT Disclosed herein is a marine propulsion device com- [22] June 1972 prising a propeller shaft supported by a lower unit and [21] Appl.'No.: 259,963 extending rearwardly through an exhaust gas opening in the lower unit, a propeller having a hub adapted for discharging exhaust gas there through and mounted on 2% F5 416/93 4 1 2 23 the rearwardly extending propeller shaft for common I d 134 rotary movement with the propeller shaft and for axial 0 416 movement relative to the propeller shaft between a l first, forwardly located position and a second position located rearwardly of the forward position with the [56] References C'ted v propeller spaced axially rearwardly of the lower unit UNlTED STATES PATENTS exhaust gas opening, together with means biasing the 3,467,051 9/1969 Shimanckas 115/34 propeller toward the rearward position. 3,556,041 1/1971 Shimanckas 115/34 3,563,670 2/1971 Knuth 416/93 8 Claims, 3 Drawmg Figures VARIABLY VENTILATED PROPELLER BACKGROUND OF INVENTION The invention relates generally to arrangements for mounting propellers affording through the hub exhaust discharge. More particularly, the invention relates to marine propulsion lower units including arrangements for mounting a through the hub propeller on a propeller shaft in such manner as to permit propeller movement axially of the propeller shaft between spaced fore and aft positions so as to selectively afford discharge of exhaust gasses either behind the propeller when the propeller is in the forward position, or when the propeller is in a rearward position, in front of the propeller through a gap between the lower unit and the rearwardly spaced propeller.

Examples of prior arrangements for mounting propellers which are adapted for through the hub" exhaust discharge include the United States Alexander Patent No. 2,948,252 issued Aug. 9, 1960; the United States Shimanckas Patent No. 3,457,051 issued Sept. 16, 1969; and the United States Knuth Patent No. 3,563,670 issued Feb. 16, 1971. Attention is also directed to the United States Strang Patent No. 3,356,151 issued Dec. 5, 1967.

SUMMARY OF THE INVENTION The invention provides a mounting arrangement for a propeller which is adapted for through the hub exhaust gas discharge, and which is shiftable axially on a propeller shaft between spaced fore and aft positions, which arrangement includes means normally biasing the propeller to the rearward or aft position. As a consequence, when an outboard motor or stem drive unit is started, exhaust gasses are permitted to escape forwardly of the propeller through a gap between the propeller and the lower unit. Such escape of the exhaust gasses causes initial propeller ventilation and permits rapid increase in engine speed, and consequent increase in the rate of propeller rotation which might not otherwise be obtainable if ventilation were not permitted and the propeller was immediately fully loaded. When using a propeller mounting arrangement in accordance with the invention, upon reaching a relatively high rotational speed, the propeller will develop suffi-v cient thrust to overcome the biasing means and will move forwardly on the propeller shaft to close the gap and to thereby prevent further exhaust gas ventilation and to provide for conventional through the hub" exhaust discharge with the propeller under full load.

Accordingly, one of the principal objects of the invention is the provision of a propeller mounting arrangement which permits a rapid increase in the rate of propeller rotation because of reduced propeller loading occasioned by ventilation, followed by cessation of ventilation and rapid assumption of full load upon attainment of a relatively high rotary speed. Such operation facilitates use of high speed propellers and gear ratios for high thrust applications, such as water skiing, etc.

Another of the principal objects of the invention is i the provision of propeller mounting arrangement including means affording shifting of the propeller on a propeller shaft between axially spaced forward and aft positions relative to the propeller shaft, together with means biasing the propeller toward the aft position.

Other objects and advantages of the invention will become known by reference to the following description and the accompanying drawings.

DRAWINGS FIG. 1 is a partially schematic, fragmentary view, partially broken away and in section, of a marine propulsion lower unit including an enlarged illustration of a mounting arrangement embodying various of the features of the invention.

FIG. 2 is a fragmentary view, similar to FIG. 1, but showing the components of the propeller mounting arrangement in another condition.

FIG. 3 is a fragmentary, end view of the propeller mounting arrangement shown in FIG. 1, with parts broken away and in section.

Before explaining the invention-in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts set forth in the following general description or illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

GENERAL DESCRIPTION Shown in the drawings is a marine propulsion device 11 which can be either an outboard motor or a stern drive unit. The marine propulsion device 11 conventionally includes a lower unit 13 which can be vertically swingable and horizontally steerible. Included in the lower unit 13 is a portion 17 which is normally submerged in water, and which includes a rearwardly facing exhaust gas discharge opening our outlet 19. Rotatably supported by the lower unit portion 17 is a propeller shaft 21 which includes a rearward portion 23 extending through the lower unit exhaust gas discharge opening 19 and rearwardly of the lower unit 13.

Included in the lower unit 13 is any suitable means for rotatably driving the propeller shaft 21, which means can include a vertically extending drive shaft 27 and a reversing transmission 29 connecting the drive shaft 27 to the propeller shaft 21.

Also included in the lower unit 13 is any suitable exhaust gas passage means 31 which communicates with the lower unit exhaust gas discharge opening 19 and with the exhaust ports of the driving engine (not shown).

Carried on the propeller shaft 21 for rotary movement in common therewith and for relative movement therebetween axially of the propeller shaft 21 is a propeller 33 which is shiftable between a first. forwardly located position shown in FIG. 2 and a second position which is shown in FIG. 1 and which is located in rearwardly spaced relation from the first or forward position and rearwardly of the exhaust gas discharge opening 19 of the lower unit 13 so as to provide an annular gap 37 (See FIG. 1) between the propeller 33 and the lower unit 13, which gap 37 communicates with the exhaust gas discharge opening 19 of the lower unit 13. The invention is not limited to the particularly illustrated propeller 33, and any propeller including an axial exhaust gas passageway including an inlet and an outlet can be modified or adapted so as to include various of the features of the invention.

The illustrated propeller 33 includes an outer hub 39 from which there extends one or more propeller blades 41 and an inner hub 43 which is connected to the outer hub 39 by one or more radially extending vanes 47 (see FIG. 3) and which is spaced inwardly of the outer hub 41 so as to define therebetween an exhaust gas passageway 49 having a forwardly located inlet 51 located in communication with the exhaust gas discharge opening 19 in the lower unit portion 17 when the propeller 33 is in the forward position. In addition, the exhaust gas passageway 49 in the propeller 33 also includes a rearwardly located outlet 53.

The propeller 33 also includes an inner sleeve 57 which is carried on the propeller shaft 21 for common rotary movement therewith and for relative movement axially thereof as well as a resilient bushing 59 which is captured between the inner sleeve 57 and inner hub 43 and which forms a slip clutch.

In accordance with the invention, means are provided for biasing the propeller toward the rearward position. While various arrangements can be employed, in the illustrated construction, such means comprises a coil spring 61 which encircles a part 63 of the propeller shaft 21, which at its rearward end, is seated against an annular seat provided by the forward end of the inner sleeve 57, and which at its forward end, is seated against a collar 67 which abuts a tapered part 69 of the propeller shaft 21. Thus, the propeller 33 is normally biased to the rearward position.

Means are provided for preventing egress of exhaust gas from the propeller outlet 53 when the propeller 33 is in the rearward position. While various arrangements can be employed, in the illustrated construction, such means comprises a member or flange 71 which is telescoped over the propeller shaft 21 rearwardly of the inner sleeve 57 of the propeller 33 and into engagement with a chamfered part 73 of the propeller shaft 33 adjacent to the rearward end of the propeller shaft 33.

The flange 71 includes a radially extending annular portion 77 including a series of circumferentially spaced holes, or openings or ports 79, together with a forwardly projecting cylindrical portion 81 which extends from the upper end of the annular portion 77 and which engages an annular recess 83 at the rearward end of the inner propeller hub 43 to prevent communication between the propeller exhaust gas passageway 49 and the ports 79 when the propeller 33 is in the rear ward position. The recess 83 at the rearward end of the inner hub 43 is defined by an outer cylindrical surface 87 adapted to interfit with the inner surfaces of the flange cylindrical portion 81 and by an annular surface 89 extending radially outwardly from the forward end of the cylindrical surface 87.

The flange 71 also includes an outer portion 91 which extends so as to engage or interfit with the outer hub 39 and thereby to close the outlet 53 of the propeller exhaust gas passageway 49 so as to thereby seal the exhaust gas passageway 49 against the discharge of exhaust gas when the propeller 33 is in the rearward position. When the propeller 33 is in the forward position, the outer flange portion 91 is spaced rearwardly of the outer propeller hub to define an annular opening 55 through which exhaust gas is discharged.

The flange 71 also serves as a means for limiting rearward movement of .the propeller 33 on the propeller shaft 21 under the bias of the spring 61 and is held against rearward movement away from the chamfered propeller part 73 by suitable means which, in the illustrated construction, comprises a nut 93 engaged on ll threaded propeller shaft part 97 extending rearwardly from the chamfered part'73, together with a cotter pin 99 which extends through a diametric bore in the pro peller shaft part 97 to releasably prevent loosening of the nut 99. Preferably, the nut 93 is tightened to such an extent so that the flange 71 rotates with the propeller shaft 21, thereby avoiding relative rotary movement between the outer hub 39 and the flange 71. Other means can also be employed to provide for rotation of the flange 71 in common with the propeller shaft 21.

Means are also provided for preventing egress of exhaust gas between the lower unit 13 and the propeller 33 when the propeller 33 is in the forward position. While other arrangements can be employed, in the illustrated construction, such means comprises provision of the outer surface of the forward end of the outer propeller hub 39 of an annular recess 119 defined by a cylindrical surface 121 and by an annular surface 123 extending radially outwardly from the rearward end of the cylindrical surface 121. When the propeller 33 is in the forward position, the cylindrical surface 123 extends into the mouth of the exhaust gas discharge opening 19in the lower unit portion 17, and the annular surface 123 extends in close proximity to the rearwadly facing margin around the exhaust gas discharge opening 19 to thereby prevent the exit of exhaust has between the lower unit 13 and the propeller 33.

Means are provided for limiting forward movement of the propeller 33 relative to the propeller shaft 21. While various arrangements can be employed, in the illustrated construction, such means comprises formation of the collar 67 with a rearwardly facing annular recess 129 defined by an outer cylindrical surface 131 adapted to be engaged by an inner cylindrical surface 133 formed at the forward end of the inner propeller hub 43, and by a radially outwardly extending annular surface 137 which projects from the forward end of the cylindrical surface 131 and which is adapted to be engaged by the forward end of the inner propeller hub 43 to limit forward movement of the propeller 33 axially of the propeller shaft 21.

A seal in the form of an O ring 151 can be provided between the propeller shaft 21 and the inner sleeve 57. In addition, bushings can be provided in the annular recess 129 in the collar 67, as well as along the rearward end of the inner sleeve 57.

If desired, a diverter ring 153 as disclosed in the United States Strang Patent No. 3,356,151 can be employed at the rear of the outer propeller hub 39 as generally disclosed in the before mentioned Strang Patent No. 3,356,l5l. In addition, if desired, a similar but oppositely oriented diverter ring 155 can be employed, generally as shown, adjacent to the radially extending surface 123 at the forward end of the outer propeller hub 39.

In operation, when the driving engine is not operating, the propeller 33 will be located by the spring 61 in the rearward position. When the engine is started, discharge of exhaust gasses through the exhaust gas passageway 49 in the propeller 33 is prevented by reason of engagement of the cylindrical portion 81 of the flange 71 with the inner propeller hub 43 and by reason of engagement of the radially outwardly extending portion 91 of the flange 71 with the outer propeller hub 39. However, due to the rearward spacing of the propeller 33 from the lower unit portion 17, discharge of exhaust gasses through the resulting gap 37 forwardly of the propeller 33 is permitted. Such initial propeller ventilation, occuring when the propeller 33 is in the rearward position, permits rapid increase in the speed of the propeller shaft 21. Such rapid rotation of the propeller 33 causes the propeller 33 to move forwardly on'the propeller shaft 21 to the forward position in which dis charge of exhaust gas from between the lower unit portion 17 and the forward end of the propeller 33 is prevented and in which exhaust gas discharge takes place through the exhaust gas passageway 49 in the propeller 33 and through the ports 79 in the flange 71 and through the axially extending annular opening 55 between the flange 71 and the rearward end of the outer propeller hub 39. The rapid initial increase in propeller rotation afforded by the invention is particularly desirable in high thrust applications, such as water skiing, etc.

Various of the features of the invention are set forth in the following claims:

What is claimed is:

l. A marine propulsion device comprising a lower unit with a portion which is normally submerged in water and which includes a rearwardly facing exhaust gas opening, a propeller shaft supported by said lower unit and extending rearwardly through said exhaust gas opening, means rotationally driving said propeller shaft, means for conducting exhaust gas to said lower unit portion, a propeller mounted on said propeller shaft rearwardly of said exhaust gas opening in said lower unit portion for common rotary movement with said propeller shaft between a first, forwardly located position and a second position located rearwardly of said forward position with said propeller spaced rearwardly of said exhaust gas opening in said lower unit portion, said propeller including an exhaust gas passageway including an inlet located at the forward end of said propeller in communication with said exhaust gas opening in said lower unit portion when said propeller is in said forward position and further including a rearwardly located outlet, and means between said lower unit and said propeller for biasing said propeller toward said rearward position.

2. A marine propulsion device in accordance with claim 1 and further including means on said propeller for preventing egress of exhaust gas between said lower unit portion and said propeller when said propeller is in said forward position.

3. A marine propulsion device in accordance with claim 1 and further including means preventing egress of exhaust gas from said propeller outlet when said propeller is in said rearward position.

4. A marine propulsion device in accordance with claim 3 wherein said means preventing egress of exhaust gas from said propeller outlet comprises a member fixed on said propeller shaft aft of said propeller and including an outwardly extending portion closing said outlet.

5. A marine propulsion device in accordance with claim 4 wherein said propeller includes radially spaced inner and outer hubs defining therebetween said outlet, and wherein said member further includes a forwardly extending cylindrical portion engageable with said inner hub when said propeller is in said rearward position, and a circumferentially spaced series of apertures located radially inwardly of said cylindrical portion, and wherein said outer portion is engageable with said outer hub when said propeller is in said rearward position.

6. A marine propulsion device in accordance with claim 1 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, at its forward end, against said collar, and seated, at its rearward end, against said propeller.

7. A marine propulsion device in accordance with claim 2 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, as its forward end, against said collar, and seated, at its rearward end, against said propeller.

8. A marine propulsion device in accordance with claim 3 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, as its forward end, against said collar, and seated, at its rearward end, against said propeller. 

1. A marine propulsion device comprising a lower unit with a portion which is normally submerged in water and which includes a rearWardly facing exhaust gas opening, a propeller shaft supported by said lower unit and extending rearwardly through said exhaust gas opening, means rotationally driving said propeller shaft, means for conducting exhaust gas to said lower unit portion, a propeller mounted on said propeller shaft rearwardly of said exhaust gas opening in said lower unit portion for common rotary movement with said propeller shaft between a first, forwardly located position and a second position located rearwardly of said forward position with said propeller spaced rearwardly of said exhaust gas opening in said lower unit portion, said propeller including an exhaust gas passageway including an inlet located at the forward end of said propeller in communication with said exhaust gas opening in said lower unit portion when said propeller is in said forward position and further including a rearwardly located outlet, and means between said lower unit and said propeller for biasing said propeller toward said rearward position.
 2. A marine propulsion device in accordance with claim 1 and further including means on said propeller for preventing egress of exhaust gas between said lower unit portion and said propeller when said propeller is in said forward position.
 3. A marine propulsion device in accordance with claim 1 and further including means preventing egress of exhaust gas from said propeller outlet when said propeller is in said rearward position.
 4. A marine propulsion device in accordance with claim 3 wherein said means preventing egress of exhaust gas from said propeller outlet comprises a member fixed on said propeller shaft aft of said propeller and including an outwardly extending portion closing said outlet.
 5. A marine propulsion device in accordance with claim 4 wherein said propeller includes radially spaced inner and outer hubs defining therebetween said outlet, and wherein said member further includes a forwardly extending cylindrical portion engageable with said inner hub when said propeller is in said rearward position, and a circumferentially spaced series of apertures located radially inwardly of said cylindrical portion, and wherein said outer portion is engageable with said outer hub when said propeller is in said rearward position.
 6. A marine propulsion device in accordance with claim 1 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, at its forward end, against said collar, and seated, at its rearward end, against said propeller.
 7. A marine propulsion device in accordance with claim 2 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, as its forward end, against said collar, and seated, at its rearward end, against said propeller.
 8. A marine propulsion device in accordance with claim 3 wherein said propeller biasing means comprises a collar fixed on said propeller shaft against forward movement relative to said propeller shaft, and a helical spring encircling said propeller shaft and seated, as its forward end, against said collar, and seated, at its rearward end, against said propeller. 